The present invention relates generally to cooling towers and, more specifically, to a cross flow evaporative heat and mass exchanger used for evaporative fluid cooling. The cross flow arrangement could be a single side or double side entry apparatus. Further, the cooling tower could comprise both a direct fluid cooling arrangement wherein air is passed over fill through which falling liquid is passed thereby cooling the liquid and an indirect cooling section wherein a fluid is passed through a coil and cooled by the liquid, usually water, falling downwardly across the coil thereby providing indirect cooling to a liquid or a gas passing through the coil.
In an induced draft single cross flow or double cross flow cooling tower, a fan is mounted on the roof outlet of the tower. This fan draws or induces air flow inwardly into the cooling tower through a sidewall or opposite sidewalls of the tower. Water or other evaporative liquid to be cooled is pumped to the top of the cooling tower structure and distributed through a series of spray nozzles. These spray nozzles emit a diffused spray of the water across the top of an appropriately selected fill medium. Such fill most typically comprised of a bundle of generally spaced parallel plastic sheets across each of which the water spray is dispersed and downwardly passed by gravity. A large surface area across which the water is dispersed on such sheets leads to good cooling by the induced air flow over such sheets. The cooled water is collected in a drain pan or sump and passed through to the desired cooling system wherein it will become heated and then pumped back to the cooling tower.
As mentioned above, the addition of an indirect cooling section in the form of a series of serpentine heat exchange conduits can be provided either above or below the fill sheets. A hot fluid or gas to be cooled or condensed enters the heat exchange conduits through an inlet header at one end of the conduits with the cool fluid exiting the conduit through a header joining the other ends of the conduit.
A concern in such cross flow cooling towers is the accumulation of algae or other biological contaminates in the drain pan. Such accumulation is usually due to incomplete flow of water through the drain pan. Such development of algae and other biological contaminates is increased with the exposure to sunlight. As the sump or drain pan must catch all flowing water from the cooling section, the design of such sump must address the both collection and drain needs to assure flow of all collected water from the sump to the drain outlet. Water treatment chemicals are used in the cooling tower sump to decrease the accumulation of such biological contaminates, but the design of the cooling tower sump and air inlet themselves can improve the resistance of the tower to forming such biological contaminates. Airborne debris that passes through the typical louver arrangement in the air inlet side or sides of the cross flow cooling tower can also contribute to the development of the biological contaminates. Accordingly, an improved design of the air inlet to eliminate of in flow of such airborne debris is also part of the present invention.